The invention relates to a wallpaper comprising a coating layer containing latex binder and pigment on top of a base paper, said coating layer containing a surface coating containing pigment and latex binder, the amount of the surface coating being at least 20 g/m.sup.2 as dry matter and the total amount of the coating layer being at least 30 g/m.sup.2 as dry matter.
Polyvinyl chloride (PVC) is now used commonly as the coating of wallpapers. Said material has been used a coating mainly because of its protecting effect, such as good resistance to moisture, fat and mechanical stress.
However, the use of PVC in coatings involves some drawbacks. One of these drawbacks is the waste problem, which on one hand is due to the recycling problems of the used wallpaper and on the other hand to the wastes of the PVC coating process itself. Another problem is the devices and chemicals required by the process itself. In the coating the polyvinyl chloride is applied as a so-called plastisol on top of a web to be coated. This kind of plastisol is composed of a plasticizing medium that is usually an ester formed by an aromatic acid and an aliphatic long-chain alcohol, e.g. dioctyl phthalate, and of fine PVC particles suspended therein. In the process a uniform solid coating is created by heating the flowing plastisol applied on top of the web approximately above 150.degree. C. For creating a decorative surface relief this kind of coating can be embossed by means of heat (so-called hot-embossing).
The aforementioned coating process requires special equipment and the use of organic aromatic chemicals causes problems of handling and waste disposal. One drawback associated with the finished product is that the PVC coating generates toxic substances when burning, for example hydrochloric acid, which decreases the fire safety of the wallpaper.
German Patent No. 2.501.684 shows a wallpaper coating where the coating contains a water-based styrene-butadiene latex as a binder as well as a pigment that can be insoluble starch or a mixture of calcium carbonate and calcium silicate. The amount of this type of coating on a base cardboard is usually 8-15 g/m.sup.2. This publication mentions the drawbacks of a coating containing solely an inorganic pigment being that it is too glossy and rough after calendering and its gravure printing properties are insufficient, and further, that the wet attrition resistance is essentially lowered after it has been embossed.
British Application Publication No. 2201613 shows a wallpaper coating containing water-based acrylic or vinyl acetate based binder together with alumina hydrate serving as a fire retardant and optionally also with an inorganic coating pigment. In a typical coating composition shown by the examples there is 100 parts alumina hydrate per 100 parts binder. The possibility to use mineral fillers is mentioned only in the description.
German Auslegeschrift No. 1771129 shows a wallpaper coating containing water-based binder and water-glass and barium sulphate as inorganic components. The large amount of water-glass causes undesirable colour. The large amount of water-soluble water-glass does not render the wallpaper suitable to be printed with water-based printing inks.